Pneumatic device for moving articles

ABSTRACT

A device for moving articles comprising a cylinder of nonferrous material, a piston including a magnet movable within said cylinder, means for controlling the admission of pressure fluid to the cylinder for moving said piston and a body disposed outside and adjacent to said cylinder, said body including a magnet, the arrangement being such that movement of said piston causes a corresponding movement of said body.



1. A device for moving articles comprising a cylinder of nonferrous material, a piston including a permanent magnet having a pole-piece on each axial side thereof, a body disposed outside and adjacent to said cylinder, said body including a permanent magnet which substantially surrounds the cylinder, there being a pole piece on each axial side of the permanent magnet included in said body, and means for controlling the admission of pressure fluid into the cylinder and exhaust of fluid from the cylinder for moving the piston in the cylinder, the attractive forces between the permanent magnets being such that movement of the piston causes corresponding movement of the body below a predetermined load on the body and such that above said predetermined load movement of the piston does not cause corresponding movement of the body.
 2. A device as claimed in claim 1, wherein the body comprises an annular magnet surrounding the cylinder and means for holding or supporting an article.
 3. A device as claimed in claim 2, wherein the means in said body for holding an article comprises a pneumatically operable gripping means.
 4. A device as claimed in claim 3, wherein at least a part of the gripping means is adapted to grip an article and is made of resilient material.
 5. A device as claimed in claim 1 wherein a port is provided at each end of the cylinder for the input of pressure fluid to, and exhaust of pressure fluid, from the cylinder.
 6. A device as claimed in claim 5, wherein a valve is provided for controlling the input of pressure fluid and the exhaust of pressure fluid from the cylinder to thereby control the movement of the piston in the cylinder.
 7. A device as claimed in claim 1 in which said body including the permanent magnet surrounds the cylinder.
 8. A device as claimed in claim 1 in which the piston includes a pLurality of permanent magnets. 